1. Field of the Invention
The present invention relates to a microfluidic device.
2. Description of the Related Art
In recent years, microfluidic devices have been used in analyzing liquid samples. The microfluidic device causes such a sample and another liquid to flow in each microchannel, and also causes chemical and biochemical reactions therein. Thus, a detection target material contained in the sample is detected (see, e.g., JP-A-2006-337221).
FIG. 10 illustrates a microfluidic device described in JP-A-2006-337221.
A microfluidic device 101 described in JP-A-2006-337221 electrochemically detects allergen contained in a sample. The microfluidic device 101 has a substrate 104 in which two substrate members 102 and 103 are stacked. A microchannel 105 is formed between the substrate members 102 and 103. The microchannel 105 includes a reaction portion 106, a detection portion 107, and a coupling portion 108 that connects the reaction portion 106 and the detection portion 107. An antibody specifically absorbing allergen contained in the sample is fixed in the reaction portion 106. An electrode 109 is provided with the detection portion 107.
A sample subjected to a pretreatment to link a predetermined enzyme to allergen is caused to flow in the microchannel 105. Allergen contained in the sample is trapped by the antibody fixed in the reaction portion 106. Then, a buffer solution containing a substrate-material to be changed by the enzyme linked to the allergen into an electrode active material is caused to flow in the microchannel 105. The substrate-material contained in the buffer solution is changed in a process, in which the buffer solution flows in the reaction portion 106, into an electrode active material by the enzyme linked to the allergen trapped in the reaction portion 106. The electrode active material reaches the detection portion 107 and acts upon the electrode 109 to thereby generate electric current. Allergen contained in the sample is detected by measuring the electric current.
In the device described in JP-A-2006-337221, the thickness (i.e., the distance between the bottom surface and the ceiling surface) of the microchannel at the detection portion 107 is set to be small, as compared with that at the reaction portion 106. This facilitates the action of the electrode active material upon the electrode 109. Accordingly, the sensitivity of the device may be enhanced.